[WIP] add initial documentation for available integrations

[davanstrien]

[WIP] PR to explore some options for documenting tools that integrate with/can use Inference Providers. The actual content is mostly a placeholder. Mostly want feedback on the structure.

The idea is to highlight all the tools that can use Inference Providers with a small guide on our side and links to the tools.

If we do one page per integration, it will look something like this, i.e. more below/above MacWhisper.

@Wauplin, we originally discussed doing a table. This would look something like:

The left column should link to the one-pager on the Hub docs, and the second column should contain an external link. I already have quite a long list of things that could go here, so this table might end up a bit long but probably it's okay to start.

Another option is not to use a table and do some light grouping, but this can get a bit messy with overlapping categories.

@Wauplin @hanouticelina let me know what you think. If you are happy with the structure of doing table + one pager, I can tidy up PR to just add one or two integrations to start. I am slightly worried that we end up maintaining docs for all of the integrations too, so we could also drop the one-pager, i.e. only do open code as a full code and don't do a page for every integration.

also cc @julien-c @pcuenca for viz.

[HuggingFaceDocBuilderDev]

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